"A strange sad man is he, with his hand always over his heart."Who said this?Who did they say it to?What does it mean?thanks

This quote is from Chapter 20.  The lines are spoken by Pearl, Hester's child.  Pearl is speaking to her mother.

The meaning of the quote has to do with who she is talking about.  When she says this, she is talking about Dimmesdale.  She wonders why he acts so differently when he is with her and her mother than he does out in public.  When they are alone, Dimmesdale acts lovingly towards her and talks to Hester, but when they are out in public he won't.

Of course, what's going on here is that Dimmesdale doesn't want to hang around with them in public because he doesn't want people to know he is Pearl's father.